Patent Literature 1 discloses a laminate of a MgO substrate/a Pt electrode/a (Bi,Na,Ba)TiO3 layer.
Patent Literature 2 discloses (NaxBiy)TiO0.5x+1.5y+2—BaTiO3 layers having various compositions of bismuth and sodium. Among them, BNT—08 7 is made of (NaxBiy)TiO0.5x+1.5y+2—BaTiO3 (x=0.29 and y=0.43).
As shown in FIG. 4 of Patent Literature 2, the maximum value of an applied electric field applicable to the BNT—08 7 is 40 kV/cm. The practical maximum value is 10 kV/cm, since an amount of a deformation is not proportional to the applied electric field when the value of the applied electric field is over 10 kV/cm, as shown in FIG. 11. It is difficult to eject an exact amount of ink, to measure an exact angular velocity, and to generate an electric power due to positive piezoelectric effect, when an piezoelectric film where the amount of the deformation is not proportional to the applied electric field is used for an ink jet head, an angular velocity sensor, and a piezoelectric generating element.
On the other hand, a higher applied electric field is required for the ejection of an exact amount of ink, for the measurement of an exact angular velocity, and for the electric power generation due to positive piezoelectric effect.